1. My sister cooks meals every day.

=> Meals are cooked by my sister every day.

2. My mother cleaned the floor yesterday.

=> The floor was cleaned by my mother yesterday.

3. My friend has written ten emails for 2 hours.

=> Ten emails have been written by my friends for 2 hours.

4. My father is painting our house.

=> Our house is being painted by my father.

5. My sister was buying some food at 11 a.m yesterday.

=> Some food was being bought by my sister at 11 a.m yesterday.

6. My brother uses a pencil to draw beautiful pictures.

=> A pencil is used by my brother to draw beautiful pictures.

7. They had finished their work before you came yesterday.

=> Their work had been finished before you came yesterday.